1. Field of the Invention:
This invention relates to heavy duty shears of the type that are mounted on backhoes and powered by hydraulic cylinders for the efficient handling of scrap and especially metal scrap and shearing the same into reuseable scrap sizes. Metal scrap from industrial buildings being dismantled occurs in many different forms and sizes from pipes of various diameters and lengths to structural beams such as I-beams, channels, angles, and the like and metal sheets and plates and various automobile and truck frames, railroad cars and the like and wherein the shear must be able to pick up, move and cut the metal pieces regardless of size or shape and without any wedging or binding action of the work pieces relative to the shears.
2. Description of the Prior Art:
Prior devices of this type are best represented by our U.S. Pat. Nos. 4,670,983 and 4,686,767. Other prior art is represented by U.S. Pat. Nos. 4,376,340, Ramun, et al., 4,403,431, Ramun, et al., 4,439,921, Ramun, et al., 4,450,625, Ramun et al., 4,519,135, LaBounty, 4,543,719, Pardoe and 4,558,515, LaBounty.
In the inventions disclosed in U.S. Pat. Nos. 4,670,983 and 4,686,767, Ramun, et al., metal cutting shears of substantially the same configuration as the shear of the present invention are disclosed. The patentable improvement comprising the present invention relates to the cutting edge portions attached to the fixed and movable blades of the shears. For example in the '983 patent, the fixed blade has an elongated hardened cutting edge portion 43 located inwardly of a pair of spaced upstanding guides 45 on a first outermost end of the fixed cast steel blade 22. The shear also has adjustable wear plates 44 positioned on the other one of the guides 45 and one of the guides 45 is pointed and sharpened for metal shearing engagement with all of the three hardened cutting portions 37, 38 and 39 of the movable blade 23 of the shear disclosed in the '983 patent.
In the present invention, the pointed and sharpened guide 45 remains in reduced width and a pair of substantially diamond-shaped changeable multiple cutting edge portions are positioned adjacent thereto to form the actual cutting edge portions of the fixed blade. Similarly, the pointed cutting end portion 37 and the cutting edge portions 38 and 39 of the movable blade of the shear of the '983 patent remain with the elongated cutting edge portion 38 being replaced by a pair of cutting edge portions, one of which is square in plan view, the other being rectangular. The square cutting edge portion is formed with eight cutting edges, four on each side, defining its peripheral edges and it is mounted for quick and easy positioning so that when one of the multiple cutting edges is worn, it may be partially removed and turned to bring a new cutting edge portion into alignment with the cutting edge of the fixed movable blade.